Jannik Sinner’s Clostebol Saga: Cleared After Two Positive Tests, Controversy Lingers
In one of tennis’s most unusual anti-doping cases, world No. 1 Jannik Sinner was twice found to have trace amounts of the banned steroid clostebol in March 2024—but ultimately avoided suspension after an independent tribunal accepted his explanation that contamination was unintentional. Here’s a detailed look at how the case unfolded, the tribunal’s ruling, WADA’s appeal and negotiated ban, and the wider implications for anti-doping in sport.
Testing Positive: The Trace of Clostebol
On March 10, 2024, during the BNP Paribas Open at Indian Wells, Sinner submitted a urine sample that detected minute quantities of clostebol. A second test on March 18 also returned positive results. The levels in both samples were extremely low—on the order of picograms per milliliter (pg/ml), which represents less than one-billionth of a gram
Clostebol is a synthetic anabolic androgenic steroid (AAS) banned under Section S1 of the WADA Prohibited List; it has no known performance-enhancing benefit at such minuscule doses. The presence of any quantity, however small, requires scrutiny under anti-doping rules
The Defense: Accidental Contamination via Massage
Sinner and his team contended that the positive tests stemmed from unintentional contamination via his physiotherapist. Giacomo Naldi had been treating a cut on his own hand with Trofodermin, a widely available over-the-counter spray in Italy containing clostebol. Between March 5 and March 13, Naldi applied the spray to his finger and subsequently gave Sinner full-body massages—including on his feet—while not wearing gloves, causing enough transdermal transfer to result in trace detection
Three independent scientific experts confirmed that this scenario was plausible and credible, reinforcing Sinner’s claim of accidental exposure
Tribunal Ruling: No Fault or Negligence
On August 15, 2024, an independent tribunal convened by Sport Resolutions ruled that Sinner bore “no fault or negligence” under the Tennis Anti-Doping Programme (TADP). As a result, he was exonerated from any period of ineligibility, though he was required to forfeit prize money and ranking points from Indian Wells—approximately $325,000 and 400 points
The tribunal concluded that given the minuscule nature of the exposure and absence of any performance benefit, there was no violation of intent. Sinner was allowed to continue competing throughout the appeal process
WADA’s Appeal and Case Resolution
Undeterred by the tribunal’s decision, the World Anti-Doping Agency (WADA) lodged an appeal to the Court of Arbitration for Sport (CAS) in September 2024, arguing that Sinner should nonetheless bear responsibility for the negligence of his entourage—particularly regarding the use of a banned substance in his support staff
Rather than proceed with a drawn-out legal battle, WADA and Sinner’s team reached a case resolution agreement in February 2025. The settlement imposed a three-month ban, to be served from February 9 to May 4, 2025, with training permitted again from April 13. No results were disqualified beyond the Indian Wells penalty, and the deal was structured so that Sinner would not miss any Grand Slam tournaments
Reaction: Support and Skepticism in the Tennis World
Sinner’s fate divided opinions across tennis. Some players—including Nick Kyrgios and Stanislas Wawrinka—criticized the outcome as lenient and unfair, questioning whether elite athletes benefited from preferential treatment. Kyrgios labeled the development a “sad day for tennis,” while Wawrinka called it evidence that he no longer “believes in a clean sport”
Meanwhile, others praised the thoroughness and independence of the initial tribunal. ATP and ITIA spokespeople emphasized that objective third-party adjudicators—not tennis insiders—made the ruling, underlining the integrity of the process
The Aftermath: Staff Changes and Career Resilience
In the wake of the controversy breaking publicly in August 2024, Sinner promptly dismissed both his physiotherapist and fitness coach, the two implicated in the incident .Remarkably, Sinner went on to have one of his most dominant seasons—claiming three Grand Slam titles (including the 2024 US Open and Australian Open) and ascending to World No. 1 status
By July 2025, Sinner rehired his former fitness coach Umberto Ferrara, suggesting a desire for continuity and focus as he prepares to defend his Cincinnati Open and US Open titles
Broader Implications: Anti‑Doping Policy and Athlete Responsibility
The Sinner case has become a flashpoint in debates over strict liability in anti-doping policy: athletes are ultimately responsible for everything consumed or administered by their entourage—even if they are entirely unaware. Although the tribunal accepted lack of intent, WADA’s appeal and subsequent settlement reaffirmed this principle by imposing a suspension on the basis of objective responsibility
Critics argue this enforcement can produce inconsistent outcomes, especially when high-profile athletes are involved. Supporters contend that the system must maintain rigid accountability to protect sport’s credibility—no matter the level of the athlete.
Conclusion
To summarize:
- Jannik Sinner twice tested positive for trace clostebol in March 2024.
- An independent tribunal cleared him in August 2024 of any fault or negligence, but stripped him of Indian Wells prize money/points.
- WADA appealed, leading to a three-month suspension served from February 9 to May 4, 2025, carefully timed to avoid missing Slams.
- The case highlighted issues of entourage responsibility, anti-doping fairness, and transparency.
- Sinner resumed top-level competition immediately—and has continued to perform at the highest tier, including winning major titles.
This episode underscores the tightrope that elite athletes walk: even inadvertent exposure to banned substances can threaten careers, and even a plausible explanation may not shield them from consequences. For Sinner, though, the tribunal’s decision, the WADA settlement, and his professional response have allowed him to emerge largely intact, albeit under a cloud of criticism and heightened scrutiny.
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